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Oarfish

Oarfish

Overview
Oarfish are large, greatly elongated, pelagic Lampriform fishes comprising the small family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Regalecidae. Found in all temperate to tropical oceans yet rarely seen, the oarfish family contains four species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in two genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

. One of these, the king of herrings
King of herrings
The king of herrings or giant oarfish, an oarfish of the family Regalecidae, is the world's longest bony fish. Rarely sighted, it is found in all the world's oceans at depths of between 300 and 1000 meters...

 (Regalecus glesne), is listed in the Guinness Book of World Records as the longest bony fish alive, at up to 17 metres (55.8 ft) in length.

The common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 oarfish is presumably in reference to either their highly compressed and elongated bodies, or to the former (but now discredited) belief that the fish "row" themselves through the water with their pelvic fins.
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Encyclopedia
Oarfish are large, greatly elongated, pelagic Lampriform fishes comprising the small family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Regalecidae. Found in all temperate to tropical oceans yet rarely seen, the oarfish family contains four species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in two genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

. One of these, the king of herrings
King of herrings
The king of herrings or giant oarfish, an oarfish of the family Regalecidae, is the world's longest bony fish. Rarely sighted, it is found in all the world's oceans at depths of between 300 and 1000 meters...

 (Regalecus glesne), is listed in the Guinness Book of World Records as the longest bony fish alive, at up to 17 metres (55.8 ft) in length.

The common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 oarfish is presumably in reference to either their highly compressed and elongated bodies, or to the former (but now discredited) belief that the fish "row" themselves through the water with their pelvic fins. The family name Regalecidae is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 regalis, meaning "royal". The occasional beachings of oarfish after storms, and their habit of lingering at the surface when sick or dying, make oarfish a probable source of many sea serpent
Sea serpent
A sea serpent or sea dragon is a type of sea monster either wholly or partly serpentine.Sightings of sea serpents have been reported for hundreds of years, and continue to be claimed today. Cryptozoologist Bruce Champagne identified more than 1,200 purported sea serpent sightings...

 tales.

Although the larger species are considered game fish
Game fish
Game fish are fish pursued for sport by recreational anglers. They can be freshwater or marine fish. Game fish can be eaten after being caught, though increasingly anglers practise catch and release to improve fish populations. Some game fish are also targeted commercially, particularly...

 and are (to a minor extent) fished commercially, oarfish are rarely caught alive; their flesh is not well regarded due to its gelatinous consistency.

Anatomy and morphology



The tapering, ribbony silver bodies of oarfish—together with an impressive, pinkish to cardinal red dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

—help explain the perception of majesty taken from rare encounters. The dorsal fin originates from above the (relatively small) eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

s and runs the entire length of the fish. Of the approximately 400 dorsal fin rays, the first 10 to 12 are elongated to varying degrees, forming a trailing crest embellished with reddish spots and flaps of skin at the ray tips. The pelvic fins are similarly elongated and adorned, reduced to 1 to 5 rays each. The pectoral fins are greatly reduced and situated low on the body. The anal fin is completely absent and the caudal fin may be reduced or absent as well, with the body tapering to a fine point. All fins lack true spines
Spine (zoology)
A spine is a hard, thorny or needle-like structure which occurs on various animals. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism. Spines are often formed of keratin...

. At least one account, from researchers in New Zealand, describes the oarfish as giving off "electric shocks" when touched.

Like other members of its order, the oarfish has a small yet highly protrusible oblique mouth with no visible teeth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...

. The body is scale
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...

less and the skin covered with easily abraded, silvery guanine. In the streamer fish (Agrostichthys parkeri), the skin is clad with hard tubercle
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....

s. All species lack gas bladder
Gas bladder
The swim bladder, gas bladder, fish maw or air bladder is an internal gas-filled organ that contributes to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without having to waste energy in swimming...

s and the number of gill raker
Gill raker
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch and are involved with filter feeding tiny prey. They are not to be confused with the gill filaments that compose the bony part of the gill. Rakers are usually present in two rows, projecting from both the...

s is variable.

Oarfish coloration is also variable; the flanks are commonly covered with irregular bluish to blackish streaks, black dots, and squiggles. These markings quickly fade following death. The king of herrings is by far the largest member of the family at a published total length of 11 metres (with unconfirmed reports of 15 metres or more) and 272 kilograms in weight. The streamer fish is known to reach 3 metres total length whilst the largest recorded specimen of Regalecus russelii measured just 540 centimetres standard length. It is probable that this little-known species can regularly reach a maximum length of at least 15.2 metres (50 ft).

Distribution


The members of the family are known to have a worldwide range. However, specific encounters with live individuals in situ
In situ
In situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...

are rare and distribution information is collated from records of oarfishes caught or washed ashore.

Ecology and life history


Rare encounters with divers and accidental catches have supplied what little is known of oarfish behaviour
Animal behaviour
Animal behaviour is the subject of:* The field of Ethology* Animal Behaviour, a scientific journal...

 and ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

. Apparently solitary animals, oarfish may frequent significant depths up to 1000 metres (3,280.8 ft). A photograph on display in bars, restaurants, guesthouses and markets around Laos
Laos
Laos Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ Sathalanalat Paxathipatai Paxaxon Lao, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west...

 and Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

 that is captioned, "Queen of Nāga
Naga
Naga or NAGA may refer to:* Nāga, a group of serpent deities in Hindu and Buddhist mythology.-People:* Nayan / Nayar/Nair people of Kerala Society* Naga people, a diverse ethnic identity in Northeast India...

s seized by American Army at Mekhong River, Laos Military Base on June 27, 1973 with the length of 7.80 metres," is a hoax
Hoax
A hoax is a deliberately fabricated falsehood made to masquerade as truth. It is distinguishable from errors in observation or judgment, or rumors, urban legends, pseudosciences or April Fools' Day events that are passed along in good faith by believers or as jokes.-Definition:The British...

. The photograph was taken by Dr. Leo Smith of The Field Museum, of an oarfish found in late 1996 by US Navy SEAL
United States Navy SEALs
The United States Navy's Sea, Air and Land Teams, commonly known as Navy SEALs, are the U.S. Navy's principal special operations force and a part of the Naval Special Warfare Command as well as the maritime component of the United States Special Operations Command.The acronym is derived from their...

 trainees on the coast of Coronado, California
Coronado, California
Coronado, also known as Coronado Island, is an affluent resort city located in San Diego County, California, 5.2 miles from downtown San Diego. Its population was 24,697 at the 2010 census, up from 24,100 at the 2000 census. U.S. News and World Report lists Coronado as one of the most expensive...

, USA
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

An oarfish measuring 3.3 metres (11 ft 4 in) and 63.5kg (140 lb) was reported to have been caught on 17 February 2003 by Ms Val Fletcher using a fishing rod
Fishing rod
A fishing rod or a fishing pole is a tool used to catch fish, usually in conjunction with the pastime of angling, and can also be used in competition casting. . A length of fishing line is attached to a long, flexible rod or pole: one end terminates in a hook for catching the fish...

 bait
Bait (luring substance)
Bait is any substance used to attract prey, e.g. in a mousetrap.-In Australia:Baiting in Australia refers to specific campaigns to control foxes, wild dogs and dingos by poisoning in areas where they are a problem...

ed with squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

, at Skinningrove
Skinningrove
Skinningrove is a village in the borough of Redcar and Cleveland and the ceremonial county of North Yorkshire, England.This name is Viking influenced and is thought to mean Skinners grove or pit...

, United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

.

Behaviour


In 2001 an oarfish was filmed alive and in situ: the 1.5 metre fish was spotted by a group of U.S. Navy personnel during the inspection of a buoy in the Bahamas http://www.nmfs.noaa.gov/speciesid/fish_page/fish82a.html. The oarfish was observed to propel itself via an amiiform mode of swimming; that is, rhythmically undulating the dorsal fin whilst keeping the body itself straight. Perhaps indicating a feeding posture, oarfish have been observed swimming in a vertical orientation, with their long axis perpendicular to the ocean surface. In this posture the downstreaming light would silhouette the oarfishes' prey, making them easier to spot.

In July 2008, scientists captured footage of the rare fish swimming in its natural habitat off the Gulf of Mexico. It is the first ever confirmed sighting of an oarfish at depth, as most specimens are discovered dying at the sea surface or washed ashore. The fish was estimated to be between 5 m and 10 m in length.

From December 2009 to March 2010, unusual numbers of the slender oarfish Regalecus russelii (竜宮の使い “Ryūgū-No-Tsukai”,) known in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese folklore
Folklore
Folklore consists of legends, music, oral history, proverbs, jokes, popular beliefs, fairy tales and customs that are the traditions of a culture, subculture, or group. It is also the set of practices through which those expressive genres are shared. The study of folklore is sometimes called...

 as the Messenger from the Sea God's Palace
Ryugu-jo
In Japanese mythology, Ryūgū-jō is the undersea palace of Ryūjin, the dragon god of the sea. Depending on the version of the legend, it is built from red and white coral, or from solid crystal. The inhabitants of the palace were Ryūjin's servants, which were various denizens of the sea...

, appeared in the waters and on the beaches of Japan; the appearance of which is said to portend earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

s.

Feeding ecology


Oarfish feed primarily on zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...

, selectively straining tiny euphausiids, shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

 and other crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s from the water. Small fish, jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...

 and squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

 are also taken. Large open-ocean carnivores are all likely predators of oarfish, and include the Oceanic whitetip shark
Oceanic whitetip shark
The oceanic whitetip shark, Carcharhinus longimanus, is a large pelagic shark inhabiting tropical and warm temperate seas. Its stocky body is most notable for its long, white-tipped, rounded fins....

.

Life history


The oceanodromous Regalecus glesne is recorded as spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 off Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 from July to December; all species are presumed to be non-guarders and release brightly coloured, buoyant eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

, up to 6 millimetre (0.236220472440945 in) across, which are incorporated into the zooplankton. The eggs hatch after about three weeks into highly active larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e, that feed on other zooplankton. The larvae have little resemblance to the adults, with long dorsal and pelvic fins and extensible mouths. Larvae and juveniles have been observed drifting just below the surface. In contrast, adult oarfish are rarely seen at the surface when not sick or injured.

Etymology and taxonomic history



The oarfish family contains four species in two genera.
  • Genus Agrostichthys
    • Streamer fish, Agrostichthys parkeri (Benham, 1904)
  • Genus Regalecus
    Regalecus
    Regalecus is a fish genus of the family Regalecidae commonly called oarfish. Several species of oarfishes have been described, but they are now all believed to be the same species Regalecus glesne.-External links:*...

    • King of herrings
      King of herrings
      The king of herrings or giant oarfish, an oarfish of the family Regalecidae, is the world's longest bony fish. Rarely sighted, it is found in all the world's oceans at depths of between 300 and 1000 meters...

      , Regalecus glesne Ascanius, 1772
    • Regalecus kinoi Castro-Aguirre, Arvizu-Martinez & Alarcon-Gonzalez, 1991
    • Regalecus russelii (Cuvier, 1816)

External links